50 lines
1.1 KiB
TypeScript
50 lines
1.1 KiB
TypeScript
import debounce from "debounce";
|
|
import {Component} from "preact";
|
|
import {log} from "../../utilities/exports.js";
|
|
|
|
type Props = Record<string, unknown>;
|
|
|
|
type State = {
|
|
hidden: boolean;
|
|
};
|
|
|
|
export class BackToTopFeature extends Component<Props, State> {
|
|
constructor() {
|
|
super();
|
|
this.state = {
|
|
hidden: true,
|
|
};
|
|
|
|
// Add a "debounced" handler to the scroll listener, this will make it so
|
|
// the handler will only run after scrolling has ended for 150ms.
|
|
window.addEventListener("scroll", debounce(this.scrollHandler, 150));
|
|
|
|
// Run the handler once in case the page was already scroll down.
|
|
this.scrollHandler();
|
|
|
|
log(`Back To Top: Initialized.`);
|
|
}
|
|
|
|
scrollHandler = () => {
|
|
this.setState({hidden: window.scrollY < 500});
|
|
};
|
|
|
|
scrollToTop = () => {
|
|
window.scrollTo({behavior: "smooth", top: 0});
|
|
};
|
|
|
|
render() {
|
|
const hidden = this.state.hidden ? "trx-hidden" : "";
|
|
|
|
return (
|
|
<a
|
|
id="trx-back-to-top"
|
|
class={`btn btn-primary ${hidden}`}
|
|
onClick={this.scrollToTop}
|
|
>
|
|
Back To Top
|
|
</a>
|
|
);
|
|
}
|
|
}
|